UNCERTAINTY IN MEASUREMENTS
When it comes to electrical measurements, precision is key. This is particularly true when we’re measuring voltage, current (both direct and alternating), and resistance. One of the tools we commonly use for these measurements is the UNIT-T UT 133B multimeter.
The UNIT-T UT 133B multimeter is a versatile device that allows us to make accurate measurements of various electrical properties. However, like all measurement tools, it comes with a degree of uncertainty. This uncertainty is outlined in the device’s manual, which provides tables detailing the potential margin of error for each type of measurement.
For instance, when measuring direct current (DC) or direct voltage (DV), the uncertainty might be expressed as a percentage of the reading plus a number of least significant digits (LSD). The same applies to measurements of alternating current (AC) or alternating voltage (AV), and resistance.
To calculate the uncertainty for a specific measurement, we would first identify the relevant row in the uncertainty table based on the range of our measurement. Then, we apply the formula provided, which typically involves multiplying the reading by the percentage uncertainty, and adding the product of the LSD and the unit of measurement.
For example, if we were measuring a resistance of 100 ohms, and the table specifies an uncertainty of 1% and 3 LSD for this range, the calculation would be as follows:
Uncertainty = (1% of 100 ohms) + (3 LSD * unit of measurement)
By understanding and applying these uncertainty calculations, we can ensure that our measurements with the UNIT-T UT 133B multimeter are as accurate and reliable as possible.
TECHNICAL SPECIFICATIONS
MEASUREMENTS
Measurements have been taken on a solar cell, an AAA battery, an electrical outlet, a resistor, a ribbon cable, and a small roll of enameled copper wire.
Different scales on the multimeter have been used to appreciate the different margins of error. For each measurement taken at each scale, 5 measurements are considered and the average of these 5 readings is used to calculate the uncertainty as indicated in the manual.
These are our measurement results:
